DotNext by Roman Sakno

<PackageReference Include="DotNext" Version="3.1.0" />

 CallerMustBeSynchronizedAttribute

Indicates that the caller of the attributed method must be synchronized.
using System; using System.ComponentModel; using System.Diagnostics; namespace DotNext.Runtime.CompilerServices { [AttributeUsage(AttributeTargets.Constructor | AttributeTargets.Method, AllowMultiple = false)] [Conditional("DEBUG")] [CLSCompliant(false)] [EditorBrowsable(EditorBrowsableState.Never)] public sealed class CallerMustBeSynchronizedAttribute : Attribute { } }